In an inspection of disks, disks before inspection accommodated in a feed cassette are taken out one by one and loaded on disk inspection machines, and when the inspection is completed, disks after inspection are unloaded from the disk inspection machines and accommodated in one of classed cassettes corresponding to classification according to the inspection result.
In order to enhance the inspection efficiency, when a disk inspection system uses a plurality of disk inspection machines to perform parallel disk inspection, number of disks inspected in a unit of time can be increased. However, when doing so, number of respective cassettes at feed side and at accommodation side increases correspondingly. In such instance, a handling system that efficiently performs an exchange of the respective cassettes and loading and unloading of the disks to the respective disk inspection machines is also necessitated.
Therefore, a disk inspection system in which feed cassettes and classed cassettes are arranged on a turntable has been proposed. In the system, disks before inspection can be continuously fed to a plurality of disk inspection machines and disks completed of the inspection are accommodated in one of the classed cassettes corresponding to the classification according to the inspection result.
For such instance, respective provisions in a disk inspection system of a relaying stand (herein after will be referred to as relay stand) for transferring disks before inspection and a relay stand for disks completed of inspection between the turntable and the plurality of disk inspection machines are disclosed and known in JP-A-4-122554 of the present assignee. The relay stands in this disk inspection system can compensate for a deviation of processing timing at the side of disk inspection machines with respect to disk feed timing from respective cassettes provided at the side of the turntable and disk accommodation timing to the respective cassettes. Further, the transferring distance for loading/unloading disks to the plurality of disk inspection machines is shortened up to the relay stand to thereby enhance the inspection efficiency.
The relay stand disclosed in JP-A-4-122554 is provided in common for the plurality of disk inspection machines. Moreover, the relay stand moves to a predetermined fixed position as a relaying point of disks by a handling robot. Further, since the loading of disks to the respective disk inspection machines has to be performed after disks after inspection are unloaded and detached therefrom, two relay stands, one relay stand for placing a disk of unloaded and the other relay stand for placing a disk before inspection are necessitated and such are respectively provided in the system.
For this reason, this disk inspection system necessitates a moving mechanism of the relay stands in which a disk after inspection set on a first relay stand and a disk before inspection set on a second relay stand are moved to relaying points where handling robots handle respective disks in response to respective transferring timings.
As a result, a disk is kept placed on the relay stand until the handling robot moves to a subsequent disk handling process, which prolongs residence time of the disk on the relay stand. Therefore, for a small disk inspection system in which small disks less than 2.5 inches required of a comparatively short inspection time are inspected in parallel, a problem of reducing inspection efficiency raises.
Further, since the quality of disks has been improved now a day, an inspection of tracks other than thinned out is performed not for an inspection of all tracks partly in view of the density increase of tracks. In this manner, since the inspection time is shortened even for disks of more than 2.5 inches, the residence time of the disk set on the relay stand in the above disk inspection system disturbs efficiency of the disk inspection.